Recently, demands for a high-resolution and high-quality image such as an HD (High Definition) image and an UHD (Ultra High Definition) image have increased in various fields of applications. As image data has higher resolution and higher quality, an amount of data more increases relative to existing image data. Accordingly, when image data is transferred using media such as existing wired and wireless broad band lines or is stored in existing storage media, the transfer cost and the storage cost increases. In order to solve these problems occurring with an increase in resolution and quality of image data, high-efficiency image compressing techniques can be utilized.
The image compressing techniques include various techniques such as an inter prediction technique of predicting pixel values included in a current picture from previous or subsequent pictures of the current picture, an intra prediction technique of predicting pixel values included in a current picture using pixel information in the current picture, and an entropy encoding technique of assigning a short code to a value with a high appearance frequency and assigning a long code to a value with a low appearance frequency. Image data can be effectively compressed and transferred or stored using such image compressing techniques.